<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>登高布局</title>
  <style>
    #parent{
      border: 10px black solid;
      overflow: hidden;
    }
    #box1{
      float: left;
      width:100px;
      background: red;
      margin-bottom: -1000px;
      padding-bottom: 1000px;
    }
    #box2{
      float: right;
      width:100px;
      background: blue;
      margin-bottom: -1000px;
      padding-bottom: 1000px;
    }
  </style>
</head>
<body>
<div id="parent">
  <div id="box1">
    <p>aaaa</p>
    <p>aaaa</p>
    <p>aaaa</p>
    <p>aaaa</p>

  </div>
  <div id="box2">
    <p>aaaa</p>
    <p>aaaa</p>
    <p>aaaa</p>
    <p>aaaa</p>
    <p>aaaa</p>
  </div>

</div>

</body>
</html>